MnZn-BASED FERRITE

ABSTRACT

A MnZn-based ferrite that can reduce the loss even when a high-frequency voltage fluctuation occurs is provided. The above MnZn-based ferrite is a MnZn-based ferrite including Fe2O3, ZnO, and MnO as main components, in which Fe2O3 is 53.2 to 56.3 mol % and ZnO is 1.0 to 9.0 mol %, with a balance of MnO, in 100 mol % of the main components, and the MnZn-based ferrite includes 0.9 to 2.0% by mass of Co 2 O 3 , 0.005 to 0.06% by mass of SiO 2 , and 0.01 to 0.06% by mass of CaO, as auxiliary components, per 100% by mass of the main components.

TECHNICAL FIELD

The present invention relates to a MnZn-based ferrite.

BACKGROUND ART

A MnZn-based ferrite has properties such as a high initial magneticpermeability, a high magnetic flux density, and easy magnetization evenin a small magnetic field, and is widely used in a communication deviceapplication, a power supply application, and the like. Various studieshave been made on a MnZn-based ferrite so as to obtain a propertyaccording to the intended application (for example, Patent Literatures 1and 2).

For example, Patent Literature 1 discloses, a specific low-loss ferritefor a liquid crystal backlight, containing main components consisting of53.0 to 54.5 mol % of Fe₂O₃ and 6 to 12 mol % of ZnO, with a balance ofMnO, and containing 200 to 1000 ppm of CaO, 0 to 300 ppm of SiO₂, and100 to 4000 ppm of CoO and further containing 50 to 500 ppm of at leastone of Nb₂O₅ and Ta₂O₅, as auxiliary components, as a ferrite thatadjusts the temperature range with the minimum power loss to 20 to 60°C.

In addition, Patent Literature 2 discloses a specific magnetic ferritematerial, containing iron oxide, zinc oxide, and manganese oxide as maincomponents, in which zinc oxide at a content in the range of 7.0 to 9.0mol % in terms of ZnO and manganese oxide at a content in the range of36.8 to 39.2 mol % in terms of MnO are contained, with a balance of ironoxide, and containing cobalt oxide as an auxiliary component in therange of 2500 to 4500 ppm in terms of Co₃O₄, as a MnZn-based magneticferrite material having a low power loss in a wide temperature band anda small temperature change in power loss.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. H9-2866

Patent Literature 2: Japanese Unexamined Patent Application PublicationNo. 2001-80952

SUMMARY OF INVENTION Technical Problem

With the downsizing and higher performance of an electronic device,increasing the switching frequency of a switching power supply to ahigher switching frequency (for example, 1 to 3 MHz) or the like isbeing studied. The core material of an inductor that constitutes aswitching power supply circuit is also required to have a low loss evenat a high switching frequency.

The present invention solves the above problems and provides aMnZn-based ferrite that can reduce the loss even when a high-frequencyvoltage fluctuation occurs.

Solution to Problem

The MnZn-based ferrite according to the present invention includesFe₂O₃, ZnO, and MnO as main components, in which

-   -   Fe₂O₃ is 53.2 to 56.3 mol % and ZnO is 1.0 to 9.0 mol %, with a        balance of MnO, in 100 mol % of the main components, and    -   the MnZn-based ferrite includes 0.9 to 2.0% by mass of Co₂O₃,        0.005 to 0.06% by mass of SiO₂, and 0.01 to 0.06% by mass of        CaO, as auxiliary components, per 100% by mass of the main        components.

One embodiment of the above MnZn-based ferrite further includes 0.03 to0.12% by mass in total of one or more selected from ZrO₂, Ta₂O₅, andNb₂O₅, as an auxiliary component, per 100% by mass of the maincomponents.

In one embodiment of the above MnZn-based ferrite, the hysteresis loopof a magnetization curve is a perminvar type.

One embodiment of the above MnZn-based ferrite has an initial magneticpermeability of 300 to 900 H/m.

One embodiment of the above MnZn-based ferrite has a residual magneticflux density (Br) of 400 mT or less.

Advantageous Effects of Invention

According to the present invention, a MnZn-based ferrite that can reducethe loss even when a high-frequency voltage fluctuation occurs isprovided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is graphs showing the hysteresis loops of Comparative Example 9,Comparative Example 10, Example 35, Example 36, Example 38, andComparative Example 12.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the MnZn-based ferrite according to the present inventionwill be described.

Unless otherwise specified, the numerical range represented by using“to” includes the lower limit value and the upper limit value thereof.

<MnZn-Based Ferrite>

The MnZn-based ferrite according to the present invention (hereinafter,also referred to as the present MnZn-based ferrite) includes Fe₂O₃, ZnO,and MnO as main components, in which Fe₂O₃ is 53.2 to 60.0 mol % and ZnOis 1.0 to 9.0 mol %, with a balance of MnO, in 100 mol % of the maincomponents, and the MnZn-based ferrite includes 0.9 to 2.0% by mass ofCo₂O₃, 0.005 to 0.06% by mass of SiO₂, and 0.01 to 0.06% by mass of CaO,as auxiliary components, per 100% by mass of the main components.

It is presumed that because the present MnZn-based ferrite has the abovecomposition, induced magnetic anisotropy is generated and the formationof the hysteresis loop into a perminvar type described later is promotedto reduce the loss when a high-frequency voltage fluctuation occurs,especially the hysteresis loss and the residual loss.

The hysteresis loop of a magnetization curve will be described withreference to FIG. 1 . FIG. 1 is graphs showing the hysteresis loops ofComparative Example 9, Comparative Example 10, Example 35, Example 36,Example 38, and Comparative Example 12 in which the amount of Co₂O₃ waschanged in Examples described later. The hysteresis loops in FIG. 1 weremeasured at an applied magnetic field of 100 A/m in the evaluationmethod “Residual magnetic flux density and hysteresis loop” of theExamples described later. Comparative Example 9 has a non-perminvar typehysteresis loop, Comparative Examples 10 and 12 each have a weakperminvar type hysteresis loop, and Examples 35, 36 and 38 each have aperminvar type hysteresis loop.

In each graph, the horizontal axis represents the magnetic field H, thevertical axis represents the magnetic flux density B, and the slope ofthe hysteresis loop in the vicinity of H=0 is the initial magneticpermeability μ. In the non-perminvar type hysteresis loop, the initialmagnetic permeability μ and the residual magnetic flux density Br eachhave a large value. On the other hand, in the perminvar type hysteresisloop, the initial magnetic permeability μ and the residual magnetic fluxdensity Br each have a small value, and the magnetic flux density Bfollows a fluctuation in the magnetic field H, and thus the differencein magnetic flux density between when the magnetic field is changed inthe positive direction and when the magnetic field is changed in thenegative direction is small.

Because the present MnZn-based ferrite has the above composition, aperminvar type hysteresis loop can be obtained. As a result, it ispresumed that the MnZn-based ferrite can reduce the hysteresis loss andthe residual loss even when a high-frequency voltage fluctuation occurs.

In the present invention, the perminvar type, the weak perminvar type,and the non-perminvar type are defined as follows.

Perminvar type: μ≤700 and Br (mT)≤300,

Weak perminvar type: 700<μ≤900 and Br (mT)≤400, or μ≤900 and 300<Br(mT)≤400, and

Non-perminvar type: 900<μ or 400<Br (mT).

The present MnZn-based ferrite includes Fe₂O₃, ZnO, and MnO as maincomponents.

Fe₂O₃ is 53.2 to 56.3 mol % in 100 mol % of the main components. WhenFe₂O₃ is 53.2 mol % or more, a perminvar type hysteresis loop can beobtained, and Fe₂O₃ is preferably 53.8 mol % or more from the viewpointof further reducing the loss. In addition, when Fe₂O₃ is 56.3 mol % orless, deterioration of the loss in a low temperature region can also besuppressed, and Fe₂O₃ is preferably 56.1 mol % or less, and morepreferably 55.9 mol % or less, from the viewpoint of further reducingthe loss.

ZnO is 1.0 to 9.0 mol % in 100 mol % of the main components. When ZnO is1.0 mol % or more, the sinterability is excellent, and the productivityof the present MnZn-based ferrite is improved. When ZnO is 9.0 mol % orless, a perminvar type hysteresis loop can be obtained, and the loss issuppressed. ZnO is preferably 6.0 mol % or less from the viewpoint offurther reducing the loss.

MnO is the balance of the main components (31 to 45.8 mol % in 100 mol %of the main components).

In addition, the present MnZn-based ferrite includes 0.9 to 2.0% by massof Co₂O₃, 0.005 to 0.06% by mass of SiO₂, and 0.01 to 0.06% by mass ofCaO, as auxiliary components, per 100% by mass of the main components.

When Co₂O₃ is 0.9% by mass or more, perminvar type formation ispromoted. In addition, when Co₂O₃ is 2.0% by mass or less, deteriorationof the loss in a low temperature region can also be suppressed, andCo₂O₃ is preferably 1.7% by mass or less.

When SiO₂ is 0.005% by mass or more, a grain boundary phase issufficiently formed to suppress the loss and also improve the strength.In addition, when SiO₂ is 0.06% by mass or less, the enlargement of acrystal grain is suppressed. SiO₂ is preferably 0.02 to 0.05% by massfrom the viewpoint of further reducing the loss.

When CaO is 0.01% by mass or more, a grain boundary phase issufficiently formed to suppress the loss and also improve the strength.When CaO is 0.06% by mass or less, the enlargement of a crystal grain issuppressed. CaO is preferably 0.03 to 0.05% by mass from the viewpointof further reducing the loss.

The present MnZn-based ferrite may further include a further componentas long as the effects of the present invention are exhibited.Preferable components include ZrO₂, Ta₂O₅, and Nb₂O₅. These componentsmay be included singly or in combinations of two or more. The totalcontent of the further component is preferably 0.03 to 0.12% by mass per100% by mass of the main components.

The present MnZn-based ferrite is preferably one in which the hysteresisloop of a magnetization curve is a perminvar type, particularly from theviewpoint of reducing the hysteresis loss and the residual loss.

The present MnZn-based ferrite preferably has an initial magneticpermeability μ as described above of 300 to 900 H/m. When the initialmagnetic permeability is within the range of 300 to 900 H/m, the loss isfurther reduced.

In addition, the present MnZn-based ferrite preferably has a residualmagnetic flux density Br of 400 mT or less.

The present MnZn-based ferrite can be suitably used, for example, as acore material of an inductor used in a switching power supply circuithaving a switching frequency of a high frequency (for example, 1 to 3MHz).

<Method for Producing the Present MnZn-Based Ferrite>

The present MnZn-based ferrite may be appropriately selected from themethods by which the above properties are obtained. Hereinafter, asuitable method for producing a MnZn-based ferrite will be describedwith reference to an example.

First, Fe₂O₃, ZnO, and MnO, which are the main components, are blendedin such a way as to have the above composition, and uniformly mixed, andgranulated. The resulting powder may be calcined at, for example, about650 to 950° C.

The resulting powder is disintegrated until the average particlediameter is less than about 1 μm, and the auxiliary components are addedto the disintegrated powder in such a way as to have the abovecomposition. The present MnZn-based ferrite can be obtained by uniformlymixing the resulting mixture and then firing the same at about 1150 to1300° C.

EXAMPLES

Hereinafter, the present invention will be specifically described withreference to Examples and Comparative Examples. The present invention isnot limited by the descriptions thereof.

Example 1

Each raw material powder was weighed and mixed such that aftersintering, the Fe₂O₃ content was 56.3 mol %, the ZnO content was 4.0 mol%, and the MnO content was 39.7 mol % to make a total of 100 mol %. Inthe mixing step, the mixture was disintegrated by using an attritoruntil the average particle size of the mixture was 1.0 μm. Next, in adrying/granulation step, when the total mass of the above mixture was100 parts by mass, 0.5 parts by mass of polyvinyl alcohol was added, andthe resulting mixture was sprayed by using a spray dryer to obtain agranule. Next, the granule was calcined at 750° C. for 1 hour in an airatmosphere to obtain a calcined product.

Raw material powders of auxiliary components, respectively, were addedsuch that SiO₂ was 0.03% by mass, CaO was 0.04% by mass, ZrO₂ was 0.075%by mass, and Co₂O₃ was 1.5% by mass, when the total mass of the obtainedcalcined product was 100 parts by mass.

Next, as a disintegration step, a mixture of the calcined product andthe additives was disintegrated by using a disintegrator such that themedian particle diameter D50 after disintegration was 0.5 μm or more and1.0 μm or less, to obtain a disintegrated powder. Next, as adrying/granulation step, when the total mass of the disintegratedproduct was 100 parts by mass, 1 part by mass of polyvinyl alcohol wasadded to the disintegrated product, and the resulting mixture wassprayed by using a spray dryer to obtain a granule. The median diameterD50 of the granule at this time was 100 μm. Next, as a molding step anda sintering step, the granule was molded into a toroidal type corehaving an outer diameter of 16 mm, an inner diameter of 10 mm, and aheight of 5 mm, and sintered at 1200° C. to obtain a sintered body(MnZn-based ferrite).

Examples 2 to 53 and Comparative Examples 1 to 12

Sintered bodies (MnZn-based ferrites) thereof were obtained in the samemanner as in Example except that in Example 1, the blending proportionsof the main components and the auxiliary components were changed to theblending proportions, respectively, shown in Tables 1 to 8.

<Evaluation Methods>

(1) Initial Magnetic Permeability

A primary winding was wound 10 times around the molded toroidal typeMnZn-based ferrite (core), and the initial magnetic permeability u at 10KHz at 23° C. was measured by using an impedance analyzer.

(2) Residual Magnetic Flux Density and Hysteresis Loop

A primary winding was wound 25 times and a secondary winding was wound25 times around the molded toroidal type core, and the hysteresis loopwhen a magnetic field of 1000 A/m was applied was measured by using a BHanalyzer to determine the residual magnetic flux density Br.

(3) Core Loss (Pcv)

A primary winding was wound 5 times and the secondary winding 5 timesaround the molded toroidal type core, and Pcv was measured by using a BHanalyzer under conditions of 1 MHz-50 mT in atmospheres of 25° C. and120° C.

Results thereof are shown in Table 1 to Table 8.

TABLE 1 Evaluation items Initial Residual Main components Auxiliarycomponents magnetic magnetic flux [mol %] [% by mass] Pcv Pcvpermeability μ density Br Hysteresis Example Fe₂O₃ MnO ZnO SiO₂ CaO ZrO₂CO₂O₃ 25° C. 120° C. [H/m] [mT] loop Comparative 56.4 39.6 4.0 0.03 0.040.075 1.5 760 320 280 330 Weak Example 1 perminvar Example 1 56.3 39.74.0 0.03 0.04 0.075 1.5 490 280 300 300 Perminvar Example 2 56.2 39.84.0 0.03 0.04 0.075 1.5 350 250 320 280 Perminvar Example 3 56.1 39.94.0 0.03 0.04 0.075 1.5 290 220 350 250 Perminvar Example 4 55.9 40.14.0 0.03 0.04 0.075 1.5 240 200 380 220 Perminvar Example 5 55.6 40.44.0 0.03 0.04 0.075 1.5 180 150 410 180 Perminvar Example 6 55.3 40.74.0 0.03 0.04 0.075 1.5 140 180 430 190 Perminvar Example 7 55.0 41.04.0 0.03 0.04 0.075 1.5 150 200 450 210 Perminvar Example 8 54.7 41.34.0 0.03 0.04 0.075 1.5 170 220 510 230 Perminvar Example 9 54.4 41.64.0 0.03 0.04 0.075 1.5 200 230 550 240 Perminvar Example 10 54.1 41.94.0 0.03 0.04 0.075 1.5 220 240 590 250 Perminvar Example 11 53.8 42.24.0 0.03 0.04 0.075 1.5 230 250 610 260 Perminvar Examela 12 53.5 42.54.0 0.03 0.04 0.075 1.5 250 260 640 260 Perminvar Example 13 53.2 42.84.0 0.03 0.04 0.075 1.5 270 280 690 270 Perminvar Comparative 53.1 42.94.0 0.03 0.04 0.075 1.5 280 300 740 280 Weak Example 2 perminvar

TABLE 2 Evaluation items Initial Residual Main components Auxiliarycomponents magnetic magnetic flux [mol %] [% by mass] Pcv Pcvpermeability μ density Br Hysteresis Example Fe₂O₃ MnO ZnO SiO₂ CaO ZrO₂CO₂O₃ 25° C. 120° C. [H/m] [mT] loop Comparative 54.1 35.9 10 0.03 0.040.075 1.5 320 360 790 300 Weak Example 3 perminvar Example 14 54.1 36.99.0 0.03 0.04 0.075 1.5 280 300 700 290 Perminvar Example 15 54.1 37.98.0 0.03 0.04 0.075 1.5 250 280 690 280 Perminvar Example 16 54.1 38.97.0 0.03 0.04 0.075 1.5 240 260 340 280 Perminvar Example 17 54.1 39.96.0 0.03 0.04 0.075 1.5 230 250 310 270 Perminvar Example 18 54.1 40.95.0 0.03 0.04 0.075 1.5 220 240 600 260 Perminvar Example 19 54.1 41.94.0 0.03 0.04 0.075 1.5 220 240 590 250 Perminvar Example 20 54.1 42.93.0 0.03 0.04 0.075 1.5 210 243 560 240 Perminvar Example 21 54.1 43.92.0 0.03 0.04 0.075 1.5 180 200 530 230 Perminvar Example 22 54.1 44.91.0 0.03 0.04 0.075 1.5 200 230 500 230 Perminvar

TABLE 3 Evaluation items Initial Residual Main components Auxiliarycomponents magnetic magnetic flux [mol %] [% by mass] Pcv Pcvpermeability μ density Br Hysteresis Example Fe₂O₃ MnO ZnO SiO₂ CaO ZrO₂CO₂O₃ 25° C. 120° C. [H/m] [mT] loop Comparative 54.1 41.9 4.0 0 0.040.075 1.5 300 340 580 250 Perminvar Example 4 Example 23 54.1 41.9 4.00.01 0.04 0.075 1.5 250 270 600 240 Perminvar Example 24 54.1 41.9 4.00.02 0.04 0.075 1.5 230 250 600 240 Perminvar Example 25 54.1 41.9 4.00.03 0.04 0.075 1.5 220 240 590 250 Perminvar Example 26 54.1 41.9 4.00.04 0.04 0.075 1.5 220 230 580 260 Perminvar Example 27 54.1 41.9 4.00.05 0.04 0.075 1.5 230 250 600 240 Perminvar Example 28 54.1 41.9 4.00.06 0.04 0.075 1.5 250 300 650 270 Perminvar Comparative 54.1 41.9 4.00.07 0.04 0.075 1.5 500 630 900 280 Weak Example 5 perminvar

TABLE 4 Evaluation items Initial Residual Main components Auxiliarycomponents magnetic magnetic flux [mol %] [% by mass] Pcv Pcvpermeability μ density Br Hysteresis Example Fe₂O₃ MnO ZnO SiO₂ CaO ZrO₂CO₂O₃ 25° C. 120° C. [H/m] [mT] loop Comparative 54.1 41.9 4.0 0.03 00.075 1.5 330 370 580 230 Perminvar Example 6 Example 29 54.1 41.9 4.00.03 0.01 0.075 1.5 270 290 580 240 Perminvar Example 30 54.1 41.9 4.00.03 0.02 0.075 1.5 250 270 590 250 Perminvar Example 31 54.1 41.9 4.00.03 0.03 0.075 1.5 230 250 580 260 Perminvar Example 32 54.1 41.9 4.00.03 0.04 0.075 1.5 220 240 590 250 Perminvar Example 33 54.1 41.9 4.00.03 0.05 0.075 1.5 230 250 620 260 Perminvar Example 34 54.1 41.9 4.00.03 0.06 0.075 1.5 260 280 640 270 Perminvar Comparative 54.1 41.9 4.00.03 0.07 0.075 1.5 550 650 880 280 Weak Example 7 perminvar

TABLE 5 Evaluation items Initial Residual Main components Auxiliarycomponents magnetic magnetic flux [mol %] [% by mass] Pcv Pcvpermeability μ density Br Hysteresis Example Fe₂O₃ MnO ZnO SiO₂ CaO ZrO₂CO₂O₃ 25° C. 120° C. [H/m] [mT] loop Comparative 54.1 41.9 4.0 0.03 0.040.075 0 1500 1100 800 470 Non-perminvar Example 8 Comparative 54.1 41.94.0 0.03 0.04 0.075 0.4 1050 700 710 410 Non-perminvar Example 9Comparative 54.1 41.9 4.0 0.03 0.04 0.075 0.6 500 380 630 330 Weakperminvar Example 10 Comparative 54.1 41.9 4.0 0.03 0.04 0.075 0.8 320310 620 310 Weak perminvar Example 11 Example 35 54.1 41.9 4.0 0.03 0.040.075 0.9 240 250 600 200 Perminvar Example 36 54.1 41.9 4.0 0.03 0.040.075 1.4 130 200 590 250 Perminvar Example 27 54.1 41.9 4.0 0.03 0.040.075 1.7 220 210 550 280 Perminvar Example 38 54.1 41.9 4.0 0.03 0.040.075 2.0 1350 230 410 300 Perminvar Comparative 54.1 41.9 4.0 0.03 0.040.075 2.2 2360 460 310 390 Weak perminvar Example 12

TABLE 6 Evaluation items Initial Residual Main components Auxiliarycomponents magnetic magnetic flux [mol %] [% by mass] Pcv Pcvpermeability μ density Br Hysteresis Example Fe₂O₃ MnO ZnO SiO₂ CaO ZrO₂CO₂O₃ 25° C. 120° C. [H/m] [mT] loop Example 39 54.1 41.9 4.0 0.03 0.040.000 1.5 330 370 560 220 Perminvar Example 40 54.1 41.9 4.0 0.03 0.040.020 1.5 320 340 570 240 Perminvar Example 41 54.1 41.9 4.0 0.03 0.040.030 1.5 270 290 590 250 Perminvar Example 42 54.1 41.9 4.0 0.03 0.040.050 1.5 230 250 580 240 Perminvar Example 43 54.1 41.9 4.0 0.03 0.040.075 1.5 220 240 590 250 Perminvar Example 44 54.1 41.9 4.0 0.03 0.040.100 1.5 230 250 630 260 Perminvar Example 45 54.1 41.9 4.0 0.03 0.040.120 1.5 260 280 640 260 Perminvar

TABLE 7 Evaluation items Initial Residual Main components Auxiliarycomponents magnetic magnetic flux [mol %] [% by mass] Pcv Pcvpermeability μ density Br Hysteresis Example Fe₂O₃ MnO ZnO SiO₂ CaO ZrO₂CO₂O₃ 25° C. 120° C. [H/m] [mT] loop Example 46 54.1 41.9 4.0 0.03 0.040 1.5 340 370 560 220 Perminvar Example 47 54.1 41.9 4.0 0.03 0.04 0.031.5 280 290 600 240 Perminvar Example 48 54.1 41.9 4.0 0.03 0.04 0.0751.5 220 240 590 250 Perminvar Example 49 54.1 41.9 4.0 0.03 0.04 0.121.5 260 270 650 250 Perminvar

TABLE 8 Evaluation items Initial Residual Main components Auxiliarycomponents magnetic magnetic flux [mol %] [% by mass] Pcv Pcvpermeability μ density Br Hysteresis Example Fe₂O₃ MnO ZnO SiO₂ CaO ZrO₂CO₂O₃ 25° C. 120° C. [H/m] [mT] loop Example 50 54.1 41.9 4.0 0.03 0.040 1.5 340 370 570 220 Perminvar Example 51 54.1 41.9 4.0 0.03 0.04 0.031.5 280 290 600 230 Perminvar Example 52 54.1 41.9 4.0 0.03 0.04 0.0751.5 230 250 590 250 Perminvar Example 53 54.1 41.9 4.0 0.03 0.04 0.121.5 270 270 650 250 Perminvar

SUMMARY OF RESULTS

It was shown that the MnZn-based ferrites of Examples 1 to 53 above eachhad a perminvar type hysteresis loop and has a reduced loss even when avoltage fluctuation at a high frequency of 1 MHz occurs, in which theMnZn-based ferrites contained Fe₂O₃, ZnO, and MnO as main components, inwhich Fe₂O₃ was 53.2 to 56.3 mol % and ZnO was 1.0 to 9.0 mol %, with abalance of MnO, in 100 mol % of the main components, and the MnZn-basedferrites contained 0.9 to 2.0% by mass of Co₂O₃, 0.005 to 0.06% by massof SiO₂, and 0.01 to 0.06% by mass of CaO, as auxiliary components, per100% by mass of the main components.

The present application claims priority based on Japanese PatentApplication No. 2020-176040 filed on Oct. 20, 2020, the disclosure ofwhich is incorporated herein by reference in its entirety.

1. A MnZn-based ferrite comprising Fe2O3, ZnO, and MnO as maincomponents, wherein Fe2O3 is 53.2 to 56.3 mol % and ZnO is 1.0 to 9.0mol %, with a balance of MnO, in 100 mol % of the main components, andthe MnZn-based ferrite comprises 0.9 to 2.0% by mass of Co2O3, 0.005 to0.06% by mass of SiO₂, and 0.01 to 0.06% by mass of CaO, as auxiliarycomponents, per 100% by mass of the main components.
 2. The MnZn-basedferrite according to claim 1, further comprising 0.03 to 0.12% by massin total of one or more selected from ZrO2, Ta2O5, and Nb2O5, as anauxiliary component, per 100% by mass of the main components.
 3. TheMnZn-based ferrite according to claim 1, wherein a hysteresis loop of amagnetization curve is a perminvar type.
 4. The MnZn-based ferriteaccording to claim 1, wherein an initial magnetic permeability is 300 to900 H/m.
 5. The MnZn-based ferrite according to claim 1, wherein aresidual magnetic flux density (Br) is 400 mT or less.